Method of utilizing the liquors obtained by subjecting pyrites cinder to chloridizing roasting and lixiviating the roasted material



April 14, 1931. A G. SUNDBERG 1,800,761 METHOD 0F UTILIZING THE LIQUORS OBTAINED BY SUBJECTING PYRITES CINDER TO CHLORIDIZING ROASTING AND LIXIVIATING THE' ROASTED MATERIAL Filed OC. l5, 1926 Patented Apr. 14, 1931 STATES .AXEL GUSTAF SUNDBERG, OF HALSINGBGBG, SVEIDEN, ASSIGNOR Tio REYMERSHOHN S GAMBA INEUESTRI AKTEBOLAG, 0F HALSNGBOLG, SWEDEN METHOD OF TILTZING THE LIQUORS OBTAINED BY SUBJECTING IP'YRITES CINDER TO CHLDRIDIZING RGASTENG AND LLXIV'IATNG THE ROASTED MATERIAL Application led October 15, 1926, Serial No. 141,889, and in Sweden Gotober 24, 1925.

The present invention relates to methods of utilizing` the liquors obtained by subjecting pyrites cinder and the like to a chloridizing roasting process and lixiviating the roasted material thus obtained.

Since the chloridizing roasting process gaines ground in the technics for the recovery or" copper from pyrites cinders and the like, a number of dierent methods have been proposed for treating the liquors obtained on liniviating the roasted ore for the purpose ot recovering, in addition to copper, also other valuable constituents present in said liquors, as for instance zinc, silver, cobalt, sulphur, etc. However, the methods hitherto proposed have not found any prac'- tical use tor the reason that they could not be carried out economically, the copper having usually been precipitated by cementation, that is to say by means of iron in the forro ot iron scrap or the like, whereby the decoppered liquor would contain considerable quantities of ferrous salts which has rendered it di'icult to extract other valuable constituents of the liquor.

rThe cementation by means of iron involves considerable drawbacks. rThus if the copper le precipitated with iron a solution is obtained 4in which the quantity of iron ion is equivalent to the quantity of copper precipitated. Prior to further treatment of this solution in order to recover the diii'erent constituents contained therein the iron must be removed. This is a very dir'hcult, circumstantial and costly procedure and has rendei-ed uneconomical most of the previously suggested methods of treating liquors from pyrites cinder in order to recover zinc, etc. A study of works onthis subject will show that none ot' the hitherto known methods has succeeded to eliminate the disadvantageous iniuence of iron in the same simple and eticient'v-.fay as the present invention.

rlhe main object of the present invention is to provide a method whereby, in addition to copper, other valuable constituents of the liquors can be economically recovered and, consequently, great values be saved which could not hitherto be utilized.

Another object of the invention is to avoid the use of iron tor the precipitation of the copper but to use for this purpose a reagent other than iron, for instance a reducing agent such as metallic zinc or a zinc compound or the like.

Another object ot the invention is to facilitate the recovery of valuable metals other than copper by reducing the volume of liquor from which said metals are to be recovered.

Still another object of the invention is to produce an extremely pure sodium sulphate from the liquor.

Other objects of the invention will be clearly understood from the following speciiication in which `an embodiment of the method forming the subject matter of the present invention will be more closely described. It is, however, to be observed, that the processes for the recovery of the constituents set forth therein are not the only ones according to which the invention may be carried ont, but that said processes may be modified in diiierent manners without departing from the spirit of the invention.

In the accompanying drawing there is illustrated in flow sheet form, a representation of the various process steps to be hereinatter described.

The roasted material is usually first lixiviated with water preferably heated to a temperature of about OOto centigrade, and then with diluted acids, usually a mixture of hydro-chloric acid and sul'phuiic acid ohtained from the waste gases formed in the chloridizing roasting process.

The liXiviation takes place in vats or basins which are filled with ore one after the other. Lixiviant is continually pumped into the vat, penetrates through the charge to the bottom of the vat and is continuously drawn off, ylhe lixiviation is thus a discontinuous process inthe sensethat the ore is lixiviated in chargesbut is rcontinuous in the sense that every charge is lixiviated continuously when VvliXiv-iation of the charge has really begun.

JV hen lixiviating in lixiviation vats for instance' water is pumped onto the vat for a certain period'of time, and then diluted acids. The lixiviation of chlorldizing roasted pyrites cinder will'result lirst in a liquor containing `al comparatively large quantity or -chlorides and later inaliquor containing a Y coinparativelylarge quantity of sulphates.

This depends not on the nature oi the lixiviant but is due to the "fact that the chlorides othge vwinetals presentare considerablyY more solubley thanthesulphates.

ln practice the lixiviation and the seperation of the liquoriselectedin the followT ing manner z A'rllhe'liqu'or first obtained` from the vat is `let into a `chloride liquor tank. @ne can tell from experience how' large quantity of chloride liquoris obtained, that is, when cornlnunica'tionto the chloride lliquor tank should `be closed and the rest of 'the washings let into the sulphate liquor tank. Y When all the liquor has beenvdrawn ofi' the copper Vand 'chloridecontehtof the sulphate liquor is de-V Q too small, ,to closel the connnunicaticui'tov the chloride. liqi'iorl tank "when lixiviating the `nent"va'tlonfa -sonewhat earlier stage than whenlixivlatingv the previous vat, wherebyr the'chlori'ne ion concentration ofthe sulphate liquor will be a little increased. It the sulphate liquor of one vatfcontains too niuch Vchlorure theconnnunication to the chloride liquor tank from the next lixiviation vat is closed/somewhat later, whereby a sulphate liquor ,containing less chlorine'is obtained;

ln practicev it is thus very-simple to regulate the relation `between the quantities of chlol?V v rine and lsulphate liquor whichin reality only Yceding stage of the process asV will be more involves observingV that thesulphate liquor Vwill contain the right quantityofv chlorine ion in elton to the copper pr'esent,

fThe liquor thus first onta-ined contains the niajor portion of they silver and Zinc oll'the roasted product and only nnnorportion or lthecopperpthe nietalsbeing present mainly inthe forni oi chloridesi whereas'the 'liquor Y robtained on continued lixiviation contains t ie 'iL-Ainajor portion ol'tlie copper 'ofthe roasted product and onlyffalininor portion otsilver,

` zinc, etc., the metals 'insaid liquorheing presi, ent'rnainly inthe'for'nirotsulphates; lhe per-V centage of rcobalt is approximately the saine. `in the twoliquors. For the'salre of simplicity said liquors will be calledWthe chloride liquor'and the sulphate liquor respectively.

' According` to the invention the ciloride liquor and the sulphate liquor areseparated, the proportion ofthe chloride liquor in relation to the sulphate liquor being preferably adapted in such a manner that the quantity of chlorine ion in the sulphate liquor is approximately equivalent or somewhat more than equivalent tothe quantity of copper Ypresent in said liquor, reckoned las cupric chloride. That isyaccording tov the present ',invention, during the lizriviation the chloride liquor corn arising" thelirst washin'ot lthe L 7 J b roasted inaterial; isV kept Jseparate frein the sulphate liquor coinprising.V subsequentwashing. vTo lr ep the liquors 'separate, communication to the'chloride liquor is closed when the percentage of sulphur in `thewashings attains a certain value. Subsequent washings are takenout as sulphate liquor. Y Thus such a quantity ot' ',chloride liquor and of suchachlorine ion concentration is'v lirst in thev sulphate liquor.renraining` after sepf aration of the chloride liquor is equ'alto the quantity of copper in Vthe sulphate liquor 7calculated as bivalent copper. liithis bethe case the entirecopper contents of the sulphate liquor canl be precipitated as CuCl without any extra addition oi other chlorides..VV On the otherhand'the chlorineion quantity fshouldv never` erice'ed its Vequivalence of bivalent copperby. too large an amount, CuCl being soluble the er'cess.l The copper 'is then precipitated separately from each of the said liquors by any known means but preter'ablyby reagents other than iron in ait least 'one' of the liquors. The' treatment 'of the' twoiliquorsfw'll beclearly set forth in thefollowing.V 'Y Y Y i The treatment of the chloride-liquor metallic Zinc-or a'zinc coinpounc which zinc c Vor Zinc compound maybe derived'froin a pre closelyA describedin the following? rlhe precipitationrnay preferably lbeca'rried out at a somewhat increased'temperature. rlhe precipitatey thus obtained is "separated by decanting, ltering in alilter press or in' any other suitable 1nanner, and is washed with water. lf4 the Zinc compound usedy for the Vprecipitation of the copper consists of'zinc hydroxide or basic zinc carbonatathe precipi-` tate obtained will,'consequently7 'mainly consist or copper hydroxideor basic copper carbonate respectively contaminated by basic zincsalts. VThe precipitate of copper is dried and rnelted in any suitable manner,'or it inay i drawn rof that the quanti-ty tot chlorine ion Y [Sil be dissolved in sulphuric acid without drying, in order to produce copper sulphate. lt is evident that the precipitate may also be treated in any other suitable manner, Jfor instance by dissolution and cenientation.

To tie filtrate thus obtained which contains Zinc, silver, cobalt, sulphur, etc., as valuable constituents, sodium sulphide is added in a quantity corresponding to the percentage of silver and of any remaining copper, whereby silver precipitates together with remaining copper, said precipitate being separated and dried. The product thus obtained is sold under the naine of cnpriterous silver powder.

The solution obtained after the separation of the silver precipitate is then treated with chloride of lime (bleaching powder) or chlo rine and sodium carbonate while supplying i heat thereto, whereby cobalt precipitates.

rlhe precipitate thus obtained, which is contaminated by Zinc, nichel and manganese, is separated, for instance in a filter press, and may then be treated in any suitable manner, for instance for the purpose of recovering metallic cobalt or cobalt oxide.

instead of using sodium sulphide for the precipitation of silver as well as oi any copper remaining in the liquor, said metals may be precipitated in any other appropriate manner, for instance by means of zinc scrap. It this latter reaction is carried out at an increased temperature, for instance at 9 o to 100O centigrade, cobalt will also precipitate. By this means, copper, silver and cobalt are obtained in metallic state, which metals may then be separated from each other in any suitable manner.

After copper, silver and cobalt have been extracted from the liquor, a solution oi cal cium chloride is added to the liquor, where by the major portion or" the sulphur present in the liquor precipitates in the forni of pure gypsum, which isseparated in any suitable manner and burnt for the purpose ot obtaining pure plaster ot Paris and the like.

rlhe sulphur in the liquor may also be recovered in another manner by coolingl the solution obtained after the separation of copper, silver and cobalt to about O centigrade or a couple of degrees below this readiiig, whereby about two thirds of the sodium sulphate present in the liquor will crystalline.

rllhe sodium sulphate is separated, and may then be treated in a manner described below.

rlhe quantity of sulphur remaining in the solution is then precipitated in the torni of gypsum as described above.

In order to remove remaining sulphate from the liquor a solution of barium chloride is added to same, whereby barium sulphate precipitates anc is separated in any appropriate manner. To the remaining solution lime water is added, whereby the zinc precipitates as Zinc hydroxide. This pretien is added to the precipitate, whereby ti cipitate is rather dicult to separate, and for the purpose of facilitating the separation the precipitation is preferably rarried out by passing carbon dioxide through the soli which carbon dioxide may be produced lime-lrilii in which the linie produced roasting limestone. Furthermore, the precipitation is pieten bly carried out at a sonicwhat increased teinperature whereby a talline precipitate ot basic zinc carbon w.. obtained which may be easily filtered. The precipitate may be washed with water, t ed and glowed, the glowing being preiieri :ly carried out at so high temperature that the material is caused to sinter, whereby the percentages of chlorine and sulphur are reduced to a minimum. The zinc oxide obtained represent-s a. material containing about of Zinc and is very suitable for the production oi metallic zinc or zinc white.

Out of the final liquor obtained after the separation oi the zinc precipitate and containing mainly calcium chloride and sodiui chloride, gypsum may be rec vered. To this end the liquor is evaporated to the desired concentration so that sodium chloride will crystallize, whereupon the gypsum is precipitated.

Part of the zinc compound obtained may be used to precipitate the copper from the chloride liquor. For this iirpose the zinc precipitate, either Zinc hydroxide or basi Zinc carbonate, is preferably used in the iindried state, whereby the precipif :non of the copper is considerably facilitated, the zinc in said precipitate being in a very active state.

The treatment of the sulphate liquor From the sulphate liquor which, as previously stated, contains mainly the major portion of the total quantity of copper and only a minor portion of the total quantity oi' Zinc and silver, the copper is first precipitated. his precipitation may be eilected in any desired manner, a reagent or reagents other than iron being used for this pur For instance, the copper may be precipitateiil in the form of cuprous chloride by means of a suitable reducing agent. .fis redueing agent cement copper may be used, preterably such cement copper which has been obtained in a preceding stage of the process.

ln order to render the precipitation more complete and to accelerate same, an excess of cement copper is preferably used. The cuprous chloride together with any excess el' cement copper are separated from the solution and this product inay be treated in any appropriate manner for the purpose ot producing metallic copper or any copper conipound desired. Preferably a chloride solucuprous chloride is dissolved, whereas any excess of undissolved cement copper is sepa ride a solution-,isobtained which is norvreany suitable mani'ier.l The solution ob i rated and returned to the vessel'in vivhic'h'ithe copper ott the sulphate liquor precipitated inthe forinfoitcuprous chloride.' llovv and Vthen said cement copper shouldy removed ,from thef process, as the saine isfgradually `enriched in" impurities.

metallicJ copper iron scrap may Vbe added v.to

saidsolution'y of cuprous chloride,` whereby, n thecopper is precipitated as cement copperv 10' inan exceedingly pure state. Part or this cement copper inay be used for the reduction of copper trom the koriginal sulphate liquor,l andthe remainingl part may be reiined in after the separation'ot the cement topp-el preferably used for d ssolvin'g Jliresh quantities of cuprous chloride. 1 For this purpose the final liquor obtained after the separation.

or" .the Zinc precipitate may also be used,

The dissolved cuprous chloride may also be treated with liine, 'the copper then precipitating inthe torni ot euprous hydroiiide. c

a Il sulphur dioxide is usen as reducing agent,

the` copper Will precipitate in the 'torri ot cuprou's- Vchloride which may gbe rseparated. from the solution and treated for the purpose oi recovering'copper orv `copper salts, for instance by cementation by means ot iron scrap or-by lime. v u. l v

After'the separation of the cuprous chlo- `li-evedv of the inaj'or po-rtion'o he chlori and contains inainly sulphates. Freni said solution all constituentsiencept the s l ion may be'v precipitated'by ad .l l carbonate or other alkaline base or ammonia,

- 'said precipitate being then separated, for in-V stance ina ilter press. Y p s The precipitate is preferably introduced into theoriginal chloride liquor, so thatthe Zinc, silver, cobalt, etci, of .the sulphate liquor may be recovered simultaneously with corresponding metals of the chloride liquor. As thevolunie of the sulphate liquor is considerably greater than that of the chloride liquor and'rsaid lsulphate liquor contains the major portion ot the 'copper of the roasted material but'only the minor portion of the Zinc, the transfer of `the precipitate oic Zinc, t cobalt, etc., obtained Jronithe sulphate liquorl into the chloride liquor involves vvthe great at :k vantage that the totalY quantity of metals Vother than copper present inthe roasted product can be recovered troni a reduced volume of liquor, so ythat such metals can be extracted economically also from the sulphate liquor.

Under certain circumstances :the percentage ot Zinc of saidprecipitate sullicient for precipitating` the total quantity of copper in the Y chloride liquor, in which case, consequently,

the zinc precipitate obtained from the ohio-1.

ride liquorfniay be Wholly treated 'for pra. ducing .metallic zinc or zinc oxideor any other In order torproduce 'Y p tained by the addition fof sodiuni carbo-nate precipitation by ineansy of c Zinc compound, butin other cases an Afaddi' tional quantity ofizincor Zinc compound is necessary, Whichis then .preferably taken precipitate 4obtained from the i from thelzinc chlorideliquo v' A .Y Y

After the separation of the lprecipitate 0bthe solution may be treated inany appropriate rmanner for the' `purpose ot` producingl crystallized sodium sulphate orsodiuin sulphate tree from Water. Preferably l the watery sodium vsulphate obtainedby coolingl the chloride liquor is iniized with this solution, so that the'sodiuni sulphate of the chloride liquor maybe recoveredsimultaneously With that oi' the sulphate liquor :tor therpurposev o producing sodium .sulphate tree fron Water. 7

Uy reagents other than iron to precipitatethe copper the `so'diuin vsulphate Will be `obtained in a very pure state.v

Vln the embodiment el theinvention de-v scribed above tvvoV precipitates containing,` copper are obtained, the one derived troni the chloride liquor and the other iironi the sulu phatezliquor. sdescribed above these pre-Y cipitates maybeY treated'separately, but, of

course, this causes unnecessary coinplicationsV in apparatus, Yunnecessary consumption of poiverand Worlr, etc. ln. order tosiniplii'y the method, these tvvo4 precipitates maybe dissolved together in a suitable solvent,the cop per being then precipitatedgitrorn thesolution "thus obtained,. iior instance by means oit cement-ation. l

lt the copper is precipitated from the tivo l` liquors in the manner describedfabove, it is obtained from the chloride liquor in the` forni ofcopper hydroxide or basic copper carbonatela-nd from the sulphate'liquor i-nthe forni of cuprous chloride, that is to say from vthe chloride liquor in the forni of bivalent.coni-4 pound., and from the sulphate vliquor in the forni of monovalent compound;l The precipitates are separated romthe liquors andV in.

`As soon as some FeGl2 is formed, lthe Vcop,- per hydroxide or the basic copper carbonate dissolves also according .to the equation:

the copper being precipitated bythe iron added in the form oia cement copper.

In this:mannerajprecipitate is obtained containing metallic copper and iron hydroxide. The last mentioned compound may be dissolvedV by acidifying the bath, for instance with acid obtained from the waste gases formed in the chloridizin-r roasting` process, but it may also be maintained and separated together with th;` copper th ici*- ric oxide being useful on refining the copper, as it relieves the copper of arsenic, forming with this element arsenite iron which goes into the slag.

After the separation of the cement copper a solution is obtained which contains chlorides, mainly ferrous chloride. This sointion may also be used to dissolve the precipitates obtained from the chloride liquor and the sulphate liquor from which solution the copper is then precipitated in the manner described above.

VVha-t I claim as new and desire to secure by Letters Patent of the United States ot America is l. A method of utilizing the liquors obtained by subjecting copper-containing pyrites cinder and the like to chloridizing roasting and lixiviating the roasted material in two stages, the rst stage using water as a lixiviant and the second stage using an acid lixiviant, comprising keeping separate the liquor obtained during the irst stage and containing salts mainly in the form ot chlorides, the chloride liquor from the liquor later obtained and containing salts mainly in the form of sulphates, the sulphate liquor, precipitating the copper separately trom each of said liquors, separating the copper precipitates, and precipitating valuable constituents other than copper from the decoppered chloride liquor.

2. A method of utilizing the liquors obtained by subjecting copper-containing pyrites cinder and the like to chloridizing roasting and liXiviating the roasted material in two stages, the iirst stage using water as a liXiviant and the second stage using an aci( lixiviant, comprising keeping separate the liquor obtained du 1ing the first stage and containing salts mainly in the form of chlorides, the chloride liquor from the liquor later obtained and containing salts mainly in the form of sulphates, the sulphate liquor, precipitating and separating the copper from the sulphate liquor, precipitating and separating valuable constitutents other than copper from the decoppered sulphate iquor, and mixing said last-mentioned precipitate with the chloride liquor.

3. A method of utilizing the liquors obtained by subjecting copper and zinc containing pyrites cinder and the like to chloridizing roasting and lixiviating the roasted materal in two stages, the first stage using water as a liXiviant and the second stage using an acid lixiviant, comprising keeping separate the liquor obtained during the first stage and containing salts mainly in the -form of chlorides, the chloride liquor from the liquor later obtained and containing` salts mainly in the form of sulphates the sulphate liquor, precipitating and separating' the copper of the sulphate liquor, precipitating and separating valuable constituents other than copper which include zinc from the Cle-coppered sulphate liquor, precipitating the copper of the chloride liquor by means of said last-mentioned precipitate, separating this copper precipitate from the solution, and precipitating valuable constituents other than copper from said solution, said constituents deriving from both said liquors.

rides, the chloride liquor from the liquor later obtained and containing salts mainly in the 'form of sulphates, the sulphat liquor, precipitating the copper separately from each of said liquors, dissolving jointly the copper precipitates in a. chloride solution, and precipitating the copper from the solution.

5. A method ot utilizing the liquors obtained by subjecting copper-containing pyrites cinder and the like to chloridizmg roasting and lixiviating the roasted material in two stages, the first stage using Water as a liXiviant and the second stage using an acid lixiviant, comprising keeping separate the liquor obtained during the lirst stage and containing salts mainly in the term of chlorides, the chloride liquor from the liquor later obtained and containing salts mainly in the form of sulphates, the sulphate liquor, preciptating the copper separately trom each ot said liquors, dissolvingjointly the copper preciptates in a suitable solvent, preciptating the copper from the solution by cementation, separating the cement copper and using the solution thus obtained with the addition ci'` acid to dissolve further quantities of copper precipitates.

6. A method o1e utilizing the liquors obtained by subjecting copper-containing pyrites cinder and the like to chloridizing roasting and lixiviat-ing the roasted material in two stages, the first stage using water as a lixiviant and the second stage using an acid 1lixiviant, comprising keeping separate the liquor obtained during the rst stage and containing salts mainly in the form of chlorides, the chloride liquor from the liquor later obtained and containing salts mainly in the form of suiphates, the sulphate liquor, precipitating the copper separately from each of said liquors, said precipitation being eifectedifrom the Chloride liqupr by meansl off iron-free' reagent, sepratng the rcopper precipitates, and' precipitating val Y Vliable constituents other than. copper from Y the deeopperednehl'erile liquor. ';7..1Ameth0d as deseribed in claim 6, said y precipitation being efee'ted from the chloride liquorby mea-11s of zinc or zinciferous materia1,`separating. the Copperipreeipitates and'y precipitating: valuable constituents other Y than copper fronigthey decoppered Chloride 1iquor, f Y

` In' testimony-whereof -VI a'iX my signature.

kAXEL GUSTAF SUNDBERG.

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